Ability Scores, Modifiers, and Pools

I have mentioned in previous posts the possibility of using ‘ability pools’ to fuel various powers and as a replacement for ability score damage and temporary effects. I wrote up a first draft at EchelonRPG.com that I will summarize here.

Echelon does not inherently need ability scores, and I have considered a few times removing them altogether.  However, since I am trying to model a better version of D&D 3.x (which has ability scores) and I think I can gain some significant benefit from their inclusion, I will use them.

Ability Scores

Echelon uses the same ability scores as D&D 3.x, with much the same interpretation as in D&D.  They are applied somewhat differently (no skill points, so obviously Intelligence no longer affects how many you get) but Strength, Dexterity, and so on all mean pretty much what they used to.

Unlike D&D 3.x, all creatures have all ability scores.  For instance, undead and constructs use Constitution to measure durability (how hard they are to ‘break’) and I have read stories where undead and constructs might both get ‘tired’ (the cauldron-born from the Chronicles of Prydain would weaken if they spent too long from Annuvin and vampires are well known for their afternoon naps, and it is easy to imagine constructs that periodically need downtime to recover their energy).  Creatures that previously had null ability scores may likely have unusually high or unusually low values, and may have specific abilities that might make them more or less irrelevant anyway, but they will be present.

Ability Score Modifiers

Ability score modifiers are calculated and applied in a simpler manner.  Take the ability score, divide by two.  Done.  No more negative modifiers for ability score.

This should work just fine.  Contested checks (attack vs. AC,  skill vs. skill, power vs. save) include the ability score modifier of both participants.  The numbers are a little bigger, but +4 vs. -1 and +9 vs. +4 is still a five-point difference and will end up with the same result.  The math involved with ‘bigger numbers’ is less of an onus that dealing with negatives, for many people.

For uncontested checks (those with static DCs) I will have to increase the DCs somewhat, but since I have to review all such things anyway in light of using Level Bonus and not skill ranks this is not a significantly greater cost.

Ability Pools

This bit is new to Echelon, and was inspired by ability pools as described in Threshold d20.

Each ability score has an associated pool of points that may be used to fuel powers.  Ability Pools replace temporary ability score changes.  I hate having to adjust a character sheet in play because of a spell or ability damage.

The base value of an Ability Pool is equal to the ability score modifier plus the character’s Level Bonus.  I could be persuaded to change the calculation to one half of the (ability score plus level), since this gives a slight benefit to having odd ability scores (13 rather than 12; 14 is clearly better than 13) and gets rid of a pathological ‘0 pool’ at first level with an ability score of one.

Spending from an Ability Pool

Various abilities, especially those from talents, can use points from an Ability Pool as a shared resource to power them.  For instance, many divine talents may allow a character to draw on the Charisma Pool to fuel various powers.  There will often be an initial power-on cost (based on the tier of the ability) and a lower maintenance cost.

Ability Pools and Conditions

If an Ability Pool is reduced to 0 (through expenditure or damage) the character is affected by a condition specific to the Pool.  For instance, a character whose Constitution Pool is reduced to 0 is fatigued.  This condition gets worse for each multiple of the base value the character is negative (a character with a base Constitution Pool of 10 might be fatigued when his Pool is reduced to 0, exhausted when it is at -10, and unconscious when it is at -20).

Temporary Ability Pool Effects

All ability damage and drain now affects the associated Ability Pool rather than the ability score itself.  This removes the need to adjust derived values (such as attack rolls, damage, rolls, hit points, saving throw bonuses, saving throw DCs, and skill bonuses) during play.  Instead, the character may lose the ability to apply the ability score without penalty (if your Constitution Pool is empty the character becomes fatigued, which has specific effect on the character) but the character may continue to draw on the Pool with increasing condition effect.

Similarly, powers that improve ability scores (such as a bull’s strength spell) now grant temporary points to the targeted Ability Pool.  The mentioned bull’s strength spell no longer gives a bonus to the Strength score, it gives (for example, I haven’t worked this out in detail) four extra points to the  Strength Pool that may be used for ‘Strength tricks’ (such as increased bonuses to Strength-based checks, or specific talents that draw on the Strength Pool).  These points are spent before the actual Pool.  Similarly, bear’s endurance or Rage might do the same thing, giving a character additional capacity before he has to draw on his normal Constitution Pool.


A character normally recovers a number of points per Ability Pool equal to the base value of the Pool.  For instance, the character above with Constitution Pool 10 recovers 10 points to his Constitution pool after each encounter.  As long as he does not overspend (or take too much damage to the pool, or a combination) he will recover the entire Pool after each encounter.

If a character has a condition applied as a result of an expended Pool, however, that condition remains until the Pool is fully recovered.  If a character is just fatigued he will have that condition until his Constitution is back to its full base value.  Barring effects that will allow further recovery (or further expenditure that slows recovery), this means that during the next encounter he will remain fatigued.  If he were exhausted he would remain so through two encounters.

I may need to change that unconscious result to something else; sleeping through three fights would be dumb… and I don’t want you-lose conditions on the tracks anyway.


  1. Doug Lampert

    To me the Constitution pool feels an aweful lot like it should be HP.

    Isn’t fatigued what happens from overusing your Strength or Dexterity pool?

    I might well get used to this idea over time, but right now it feels wierd. I think of Con as passive, and of pools as active.

    What does a point from the con pool DO?! If poison or disableing conditions are ubiquitous I could see con pool being spent to resist (rather than using a fort save just spend from the pool). I could see the con pool acting sort of like a 4th edition healing surge (using a healing power on someone normally costs the target a point or two of con pool and barbarians can maybe spend them in combat to recover quickly on their own).

    If pools never give “you lose” conditions (which I approve of), then I think the second condition on every track needs to include a “and you may no longer voluntarily spend points from this pool” condition, and the third condition or so needs a “points lost from this pool in excess of 2x the initial value are also applied as 5x the amount of excess loss HP damage” or something similar.

    I suspect without a hard limit your characters will implausibly overdo it sometimes.

    Still, overall I like the looks of this.

  2. I’m still a little nebulous on all the potential uses of the pools might be… and Constitution is a tough one anyway. I’m certainly not attached to any particular condition for any particular ability score, but fatigue seemed reasonable for Constitution because the character has burned all of that pool. I can imagine (but am unlikely to implement) that overdoing anything could burn Constitution and thus lead to fatigue, but I’m not sure I want to go there.

    On the other hand, maybe Constitution might be a generic pool — since there’s nothing that particularly uses Constitution actively (no skill checks to mention, even Concentration in D&D 3.x feels contrived) maybe any power can draw from the Constitution pool. If you overdo Strength tricks but don’t want to take on a condition, you can burn Constitution (similarly for Dexterity, etc.)

    Healing surges and the barbarian trick (perhaps he can spend for temporary hit points as part of going into a rage?) were certainly a couple of ideas I had for using Constitution. If possible I’d like to see some common ability score tricks. Maybe spending one point from a pool gives +2 to checks using the associated ability score for a time. If there are ‘ability score’ talents such as ‘Great Strength’, maybe instead of specific abilities it allows you to spend more pool for bigger bonuses (Basic Strength gives you +2 Strength Pool and you get +4 per Pool spent up to 1, Expert gives you +4 Pool and you get +4 per Pool spent up to 2, etc. Maybe the bonus multiplier increases as well, but being able to spend six Pool at x12 makes for +72… which I’ll grant certainly gives impressive results but is so many multiples of the RNG I don’t even want to think too hard about it.

    However, I expect ‘Great Fortitude’ would certainly draw on the Constitution Pool, just as ‘Lightning Reflexes’ draws on Dexterity. I don’t yet know what these talents would look like, but I would expect some moderate bonuses to saves and abilities specific to the type of save. Great Fortitude might give you the ability to spend for neutralize poison (on yourself, at least, though I’m not horribly offended by the idea of someone high enough tier being so tough if rubs off on his friends…).

    Second condition on the track disallowing voluntary expenditure makes sense, I’ll include that. You can’t spend after being reduced to -2*base, but you can spend yourself into it (from -2*base+1 to -2*base-lots). I earlier considered limiting voluntary expenditure just down to 0 (which may make it effective to drain the top of the Pool to prevent its use) but I like the idea of someone spending himself into inconvenience, and there really does need to be a limit. The conversion of Pool reduction after that straight to damage also makes sense (conversion rate may vary). It makes it possible to kill someone by sapping an Ability Pool far enough (“I’ll stupid him to death!”) without making it as easy as D&D 3.x.

    I’m glad you like how this looks, and thanks for the feedback. I think I’m onto something good here that can use some polishing.

  3. hadsil

    I like it. It’s different. It would take getting used to, but it reads fun so that means there’s a good chance it would play fun.

    As an aside, when using the level bonus try not to fall into 4E’s error of making it meaningless. In 4E, DCs depend on the level of the character as opposed to the difficulty of the task. If something is (for example purposes) DC 20 at level 1, it’s DC 30 at level 10, DC 40 at level 20. Instead, if something is DC 20 at level 1, it should remain DC 20 at levels 10 and 20.

    Take swinging from a chandelier. If it’s a hard task, 4E would increase the DC depending upon the character’s level, meaning it will always have the same percentage chance of success or failure. However, the chandelier does not know the level of the one trying to swing. It’s an inanimate object of some engineering to use. A 20th level character should not have the same percentage chance of falling as a 1st level character unless the chandelier would fall at any attempt whatsoever to swing from it. He’s just that good.

  4. As for the Level Bonus becoming “meaningless”, while I haven’t read the 4e rules regarding it I can see why it might be taken that way.

    In Echelon, whether or not I take tussock’s advice and make everything static DC, the same task under the same circumstances will have a fixed DC. That is, slackrope walking across the street (on a clothesline, say) might be DC 25. It will be DC 25 under the same conditions for everyone, first level Dex 10 (+0 LB, +5 Dex) and 24th level Dex 28 (+12 LB, +14 Dex). As you said, the high-level guy is just that good.

    The circumstances could be different, though. The level 1 guy might be doing it under calm conditions, in good light, and slowly. The level 24 guy might be running in a storm of hail and lightning (poor lighting, wind, hit and blinded by stinging hail and lightning); the level 24 guy should find it somewhat more difficult.

    Of course, the level 24 guy is more probably doing this on a thread across a chasm on the 387th layer of the Abyss, so the example is a little off….

    I think what they intended (and the way I would do it) is that challenges ‘appropriate for level’, whatever that means, are expected to pass about half the time. This means that the baseline is going to be pegged at least in part to the Level Bonus.

    So, if you want to swing on the chandelier at the Winter Ball held by the Compte de Marchiesse, it’s a DC 20 check regardless of your level (he deliberately hangs it low and it’s got good handles for just this sort of antic, he finds them amusing. This is likely a good baseline Basic DC for someone ‘competent’ (+4 for trained Tumble, +5 for Dex 10 (or +9 for Dex 18) and +0 for Level Bonus gives +9 total — about 50% chance of success, all else being equal). Le Compte gets to see some of the dashing young men throw themselves off high things and swing (and a few number of them smash face-first into the floor, excellent!). The more capable individuals (Experts and up) will have a better chance of getting it right because they’re just better at this sort of thing, but it’s still not an overpowering advantage.

    Of course, the guy with Expert Tumble may have the same base bonus, but can spend from his Dexterity Pool to improve his chances (spend from the Pool for a straight bonus) or perhaps attack someone (foot, fist, or sword — or candle he just grabbed from the chandelier?) as he swings. The Basic-competent guy can swing from the chandelier to get away from someone or get through a crowded room, the Expert gets to do more, and is better at it anyway.

  5. GreyKnight

    I think Doug’s on the money with the point about HP. Particularly I note that (a) side-effects of Con damage occur at multiples of your Con score, and (b) your HP are currently defined to be a multiple of your Con score. So if an example character has a Con pool that can range from +Con to -5*Con, and HP equal to 6*Con, can you just make them the same thing? Removing HP would mean you only need rules for tracking ability damage and don’t have to worry about interaction with HP damage, so fewer things to keep track of. I think historically HP has “included” things such as luck and training in avoiding blows as well as physical toughness, but then again we’ve had luck/dodge bonuses to AC for ages now, so you could just split those off….

    One effect of this would be that characters can typically suffer the same amount of physical damage across their careers (which is realistic), so you would need to look over the amounts of damage caused by different effects, particularly the direct-damage spells of course. This also implies that the fighter can still dish out a meaningful amount of damage even at high levels (cut a human’s head off, he’s dead no matter how high-level he is). The bottom-most negative-multiple of Con produces the “dying” condition; meaning that tougher characters get a wider range here, rather than the flat 10 HP safety net everyone gets in 3.5e.

    Nonlethal damage could perhaps be turned into Str/Dex damage? It feels appropriate to have it separated somehow. Effects like environmental temperature and starvation currently have you make a Fort/Con check to see if you take damage, so high-Con characters are better at it either way.

    You could say that the martial training bonus to AC currently provides some dodging ability, if the above is implemented then perhaps an opening should be provided for people who want to get really, really good at dodging attacks. “Extraordinary toughness” of the sort currently exhibited by some PCs can be filled in with damage reduction; it’s the sort of thing DR does anyway. Perhaps the Toughness talent can provide DR x/— instead of bonus hit points.

    Luck is another question. Certainly characters who rely on unnaturally good luck to stay alive is a trope, so it’s not unreasonable to support it. A luck bonus to AC doesn’t feel right somehow, but I don’t know what would work. One possibility I considered was DR x/(evil or good); your luck can reduce a serious blow to a scratch, but supernatural beings are beyond the reach of mortal fortune. IDK ¯\_(°_°)_/¯

  6. GreyKnight, I may be misunderstanding your math here. On the other hand, I’ve had about 2/3 the sleep I should over the last three nights so I may be a little thicker than usual.

    Your Constitution Pool is equal to Con/2+LB. Per earlier conversation with Doug the progression is something like

    0 < Pool <= BasePool              everything's normal
    -BasePool < Pool <= 0             mild condition
    -2BasePool <= Pool <= -BasePool   more severe condition

    and anything after that gets converted to hit point damage (at some ratio or another).

    A fifth-level character (starting PC) with Con 14 has a ConPool of 9 (Con/2=7, +2 LB). As long as he keeps it above 0 he's in nominal condition, when it's from -8..0 he's fatigued (for the sake of argument), from -18..-9 he's exhausted and cannot voluntarily spend ConPool.

    Incidentally, I think I'll change the hit point calculation from BAB*Con to BAB*BaseConPool. I'll explain more in a full post.

    Ah, I see where you got the "6*Con" thing that was confusing me. Yes, a particular character in the old model might have hit points equal to 6*Con, for a time, but that would e different whenever his BAB was not equal to 6. This feels like you picked an unfortunate example for comparison... especially since I don't remember anywhere that let you take your ConPool to -5*Con.

    If I've missed something, let me know. I could have completely misunderstood what you were doing here.

  7. GreyKnight

    Oh, no, I’ve completely gotten all the numbers in that comment wrong (it was still kind of early morning here at the time). But I still like the general idea of using the Con pool in place of hit points, just the numbers I mentioned don’t work out. :-D

  8. Ah, okay. I thought that might have been what happened.

    I’m not certain the Con Pool would be a good choice. Never mind the inertia involved (D&D has always had hit points), I think it doesn’t scale well enough to act as damage mitigation and life preservation.

    HOL (Human Occupied Landfill) had static hit point values — everyone had 20 — and explicitly mitigated by reducing damage by toughness. In some fashion or another, I don’t remember the exact mechanism. D&D and relatively static hit points (ConPool) would not, I think, work as well as the existing hit point model.

  9. DougL: your comment

    “What does a point from the con pool DO?! If poison or disableing conditions are ubiquitous I could see con pool being spent to resist (rather than using a fort save just spend from the pool). I could see the con pool acting sort of like a 4th edition healing surge (using a healing power on someone normally costs the target a point or two of con pool and barbarians can maybe spend them in combat to recover quickly on their own).”

    Made me think for a moment. I don’t like the idea of having to spend from ConPool to avoid certain effects, it makes those effects unavoidable (you might not take the 3d6 Int damage — damage to your IntPool — but you will spend from your ConPool). I’m all in favor of having the ability, or potentially having the ability if it requires a talent, to spend from your ConPool to mitigate or avoid negative affects.

    Which led me to another thought. Consider, what is your base ConPool? Level Bonus + ConModifier. Your base Fortitude save? … Level Bonus + ConModifier.

    Let’s lose saving throws as a separate calculations and variables. Your base save is equal to the associated Ability Pool base value, so just use that.

    The only down side I can see to this is the potential for the ‘defense inflation’ you mention from time to time, that instead of three saves there could be seen to be six. As an abstraction, though, I can see value. I know of people who already split various saves into two ability scores each (resist illusions using Will+mWis because this is a ‘perceptive’ save, but resist mind control using Will+mCha because it is a ‘force of will’ save, for example), so providing a generic mechanism for resisting effects that happily uses something we’re already calculating seems a good idea.

  10. Regarding the ‘defense inflation’ I just mentioned, even that shouldn’t be too bad because it still ultimately leads to hit point ablation to actually kill people, so even then it’s not horrendous. Even if you can target a ‘weak save’ (and even that shouldn’t be such a big separation, especially if the range of ability scores is kept narrow) you’re only ‘more likely’ to cause damage, not play a You-Lose card.

  11. hadsil

    I’m not a fan of having the same “hit points” regardless of level. I like the bigger numbers. If 30 points of damage kills you at level 1, level 10, and level 20, then what’s the point of leveling? If at level 1 I do some attack that deals 5 damage, what’s the damage at level 10, level 20?

    That’s one of my issues with 4E. Sure, the numbers do get bigger, but it’s very slow. A level X power deals Y dice of damage. A level X + 1 power deals Y + 1 dice of damage. It’s meaningless. If it’s Y + 3 dice of damage, that’s a daily. Big whoop.

    I like the level system of D&D. I want a higher level to mean something. I want to be able to dish out more mojo and be able to withstand that more mojo from others. The relative percentage changes. Example: level 1 Fighter has 10 hit points. Opponent attacks for 4 damage. That’s 40% of his hit points. Level 10 Fighter has 100 hit points. An opponent is not necessarily going to attack for 40 hit points. Possible, yes. That’s the BBEG or his Lieutenant. Typical combats opponents deal somethingteen damage. Those 100 hit points are suppose to last.

  12. Out of curiosity, what other purpose does the ability score do? Would it be simpler to just divide the ability scores by 2? For example, instead of having an 18 strength for a bonus of 9, why not just have a strength of 9, which gives you the bonus of 9?

  13. Jack, you raise an interesting question. I may be keeping to 3-18 out of habit, perhaps. I know a lot of people (coming from D&D-land) recognize 3-18 as a more comfortable range.

    It does still tie somewhat into ability score generation, and I’m still considering having a capstone ability that gives +1 to all ability scores (per tier) that works better if I keep the 3-18 range.

    I do see benefit to not having to divide by two, since apart from ability score generation (and tradition) there may not be much point to not simplifying.

    Or it might just be inertia.

    I’ll need to take this away and think about it. Thanks.

    • The more I think about it, the more I realize the only halfway compelling argument I have for not switching from 3-18 to 1-9 is tradition. I can live with what this does to ability score generation because I use a more or less straight-up point buy (I usually apply it with a random element, but cost is linear by value — 18 == 18 points). Ability score advancement, done individually, was always in multiples of two, so that’s no problem, if I even bother to include it given that ability score modifier is currently always used with Level Bonus anyway. The only place I might run into difficulty is that “+1 to all ability scores” capstone I mentioned… and that probably isn’t really needed any more either because of the Level Bonus.

      So, tradition’s really the only reason to keep the 3-18 range rather than switch to a 1-9… and I think the increased overall simplicity makes that change worthwhile.

      Thanks Jack.

  14. Doug Lampert

    If you want to go back to 0 based average, it’s easy to do once you eliminate the divide by 2 and subtract 5 rule. Just declare that 0 is human average ability, and things less than human average have a negative score. This messes with pools some, but can be dealt with easily enough.

    Just have a rule that if the calculated pool maximum is 0 or less than the actual maximum value is 1 and the pool can never be spent voluntarily. Done.

    I feel the urge to correct one of Hadsil’s claims about 4th ed.

    The skills in fourth ed have set DCs for their tasks. This is in the rules for the skills in the PHB and quite clear, the skill writeups include DCs for the common tasks with those skills, and the DCs do not in ANY WAY depend on the PCs level.

    It’s the exact same as in 3.x that way. What’s different is that they’re explicit that tasks appropriate to challenge a level N party should have a particular DC, and give a table with the appropriate DCs. Swinging from the same chandralier DOES NOT grow in DC, but it’s assumed that your Epic character is swinging from a chandalier made of fragile ice crystals hanging over a windy crevas, while on fire, and that the DC is thus appropriately harder.

    But that “DCs also scale with level” is a common complaint about 4th ed, despite the fact that you CAN’T actually read the rules in the PHB for how your skills work without encountering set DCs for all the skills does show that you have to be very clear in your rules that the reason higher level characters face higher DCs is because they’re attempting harder, more epic tasks.

    • I considered going back to 0-based average, but I think the numbers work better this way. The ‘best’ at fifth level ‘career start’ (Str 18:9 + 2 -> pool 11) is only about half again as good as ‘normal’ (Str 10:5 + 2 -> pool 7), normalizing to zero before adding level bonus changes this to about three times as good (Str 18:4+2 = 6 vs. Str 10:0+2 = 2).

      The smaller numbers also, I think, make it harder to have differing amounts of ‘ability damage’. Right now, 1d6 Strength damage is worrisome, 2d6 stands a good chance of leaving a normal person (Str 10) weak, and 4d6 is probably enough to leave a normal person two-conditions-down (and thus unable to voluntarily use Strength pool and possibly even taking real damage). These are pretty nice numbers (dice) to work with. It seems that going with smaller pools would increase the value of ability damage to where it again becomes a preferred damage path.

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